Add Docker install helper for first-run setup

When Docker isn't detected on startup, surface a dialog offering a
one-click install (pkexec + get.docker.com on Linux, brew cask on
macOS, winget on Windows) with a graceful fallback to manual steps
and a link to official documentation. Install output streams back
to the UI via a tauri event.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/src-tauri/src/commands/install_helper_commands.rs

@@ -0,0 +1,11 @@
+use crate::install_helper::{self, InstallOptions};
+
+#[tauri::command]
+pub async fn detect_install_options() -> Result<InstallOptions, String> {
+    Ok(install_helper::detect_install_options())
+}
+
+#[tauri::command]
+pub async fn run_docker_install(app_handle: tauri::AppHandle) -> Result<(), String> {
+    install_helper::platform::run_install(&app_handle).await
+}

app/src-tauri/src/commands/mod.rs

@@ -2,6 +2,7 @@ pub mod aws_commands;
 pub mod docker_commands;
 pub mod file_commands;
 pub mod help_commands;
+pub mod install_helper_commands;
 pub mod mcp_commands;
 pub mod project_commands;
 pub mod settings_commands;